Metallizable multi-ply film

Abstract

A metallizable, sealable, biaxially stretch-oriented multi-ply film comprises a base layer essentially of polypropylene, a first polyolefinic facing layer and a second polyolefinic facing layer. All of the layers contain a neutralizing agent and a stabilizer against thermal degradation. The neutralizing agent is a calcium carbonate having an absolute particle size of less than 10.0 μm, a mean particle size of less than 0.1 μm, a specific surface area of more than 40 m 2 /g and a whiteness of more than 90% and, the stabilizer comprises a phenolic stabilizer having a molecular weight of more than 1,000 g/mol. One polyolefinic facing layer contains an anti-blocking agent. In addition, a process for producing the metallizable multi-ply film is described, and its use as a packaging material is indicated.

What is claimed is: 
     
       1. A metallizable, sealable, biaxially stretch-oriented multi-ply film, consisting essentially of a base layer comprised predominantly of propylene;   a first polyolefinic facing layer on a first side of said base layer;   a second polyolefinic facing layer on a second side of said base layer;   each of said layers containing a neutralizing agent, comprising a calcium carbonate having an absolute particle size of less than about 10 μm, a mean particle size of less than about 0.1 μm, a specific surface area of more than about 40 m 2  /g and a whiteness of more than about 90%, in a quantity of from about 0.01% to 0.2% by weight, relative to the weight of the layer, and a stabilizer against thermal degradation comprising a phenolic stabilizer having a molecular weight of more than about 1000 g/mol; and   wherein one polyolefinic facing layer contains an anti-blocking agent.   
     
     
       2. A film as claimed in claim 1, wherein at least one polyolefinic facing layer is heat-sealable. 
     
     
       3. A film as claimed in claim 2, wherein the heat-sealable facing layer contains an anti-blocking agent. 
     
     
       4. A film as claimed in claim 1, wherein one polyolefinic facing layer is non-heat-sealable. 
     
     
       5. A film as claimed in claim 4, wherein the non-sealable facing layer has been corona-treated. 
     
     
       6. A film as claimed in claim 4, wherein the non-sealable facing layer contains a saturated hydrocarbon resin. 
     
     
       7. A film as claimed in claim 6, wherein the hydrocarbon resin comprises a hydrogenated cyclopentadiene resin which is present in a quantity from about 2% to 12% by weight, relative to the weight of the facing layer. 
     
     
       8. A film as claimed in claim 2, wherein the sealable layer contains the anti-blocking agent in a quantity from about 0.1% to 0.7% by weight, relative to the weight of this layer. 
     
     
       9. A film as claimed in claim 8, wherein the anti-blocking agent contains silica or aluminum silicate. 
     
     
       10. A film as claimed in claim 1, which has an overall thickness from about 10 to 40 μm, the facing layers each being from about 0.2 to 0.7 μm thick. 
     
     
       11. A film as claimed in claim 5, further comprising a metal layer metallized or laminated to the outside of the non-sealable, surface-treated facing layer. 
     
     
       12. A film as claimed in claim 11, wherein the metal layer comprises aluminum applied by vacuum vapor-deposition. 
     
     
       13. A film as claimed in claim 11, wherein the metal layer comprises an aluminum foil. 
     
     
       14. A film as claimed in claim 11, wherein the metal layer is bonded to the non-sealable, surface-treated layer by means of a solvent-free, two-component adhesive. 
     
     
       15. A film comprising a film as claimed in claim 11, further comprising a protective coating on the outside of the metal layer. 
     
     
       16. A film as claimed in claim 15, wherein the protective coating comprises a polyolefinic protective coating. 
     
     
       17. A film as claimed in claim 16, wherein the protective coating comprises a polyethylene film or a polypropylene film or a polyester film. 
     
     
       18. A film as claimed in claim 15, which is doubled on itself via its sealable facing layer or is bonded via this facing layer to a single-ply or two-ply polypropylene film. 
     
     
       19. A packaging film, especially in a film composite or paper composite, comprising a multi-ply film as defined by claim 1.